A ratchet wrench is a type of wrench having ends that surround the nut or head of a bolt. The wrench provides a mechanical advantage by applying torque to turn bolts, nuts or other items designed to interface with a wrench. The ratcheting mechanism allows the nut or bolt to be tightened or loosened with a reciprocating motion of the wrench, without requiring that the wrench be removed, refitted, and repositioned after each turn.
A ratchet wrench includes ratchet and pawl components known in the mechanical arts to control and secure movement. Ratchets consist of a ratchet wheel, and may include a spring assembly which applies pressure to a pivoting spring loaded finger called a pawl that engages the teeth. Either the teeth, or the pawl, are slanted at an angle, so that when the teeth are moving in one direction, the pawl slides up and over each tooth in turn, with the spring forcing it back with a ‘click’ into the depression before the next tooth. When the teeth are moving in the other direction, the angle of the pawl causes it to catch against a tooth and stop further motion in that direction.
More specifically, a pawl is a movable component which operates as a lever and which includes protuberances which engage a ratchet. The pawl is used to control the direction of the ratchet. In various embodiments, bolt engaging components may be used to apply pressure to a pawl (e.g., a spring loaded component) to keep a pawl engaged within the teeth of a ratchet. A pawl may be machined, stamped or molded and constructed of one or more components having singular or multiple protuberances.
Generally, a ratchet wheel is similar to other types of gear wheels, except that its teeth or cogs may be cut with a sloped side and a “straight” or “offcut” side. That is in contrast to the two sloped sides of the tooth or cog on a regular gear wheel. Additionally, there is usually a curve in the slope of the “regular” side that acts as a ramp for the pawl to ride on. The pawl, which is usually spring loaded to keep it engaged with the teeth, will, when the ratchet wheel is rotated in one direction, slide up or “climb” the slanted or sloped side of a tooth. The pawl will then “jump” down into the bottom of the tooth space after going over the tip of the tooth, and the spring will have pushed it there. It will then ride up the next slope on the next tooth as the ratchet wheel moves in the same “forward” direction. But if the ratchet wheel is rotated in a “backward” direction, the pawl will only allow movement until it comes in contact with the “straight” side of the next tooth back and it will jam there. This will limit backward movement of the ratchet wheel to a tooth length and no more, as long as the pawl is acting normally to check the backward rotation.
Reversible ratchet wrenches are also known in the art. A reversible ratchet wrench has a handle portion and a head portion. Key features of a reversible ratchet wrench include one or two pawls having teeth which alternately engage the teeth on a ratchet wheel. In the case of two pawls, both pawls typically share a common pivot point. A lever determines the direction in which torque force is applied by engaging one pawl or the other. As seen in ratchet wrenches known in the art, one of the two pawls will engage the ratchet while the other pawl does not. One pawl will contain protuberances or teeth adapted to allow the ratchet to apply torque in one direction while the other pawl contains protuberance or teeth in an opposite configuration to allow the ratchet to apply torque in the other direction. Likewise, when a single pawl assembly is used, only one side of the pawl is engaged at a time. The torque force of the ratchet is alternately applied, the pressure released, and the ratchet wrench repositioned for the next application of torque force.
One problem generally known in the art with box type wrenches using ratchet and pawl systems is that the head of the wrench is generally closed, and threaded components (such as brake lines) will not allow the wrench to fit over them.
Various attempts are known in the art to create an open-ended ratchet wrench. However, these wrenches require a large rotational degree in order to use the wrench which is not possible in confined spaces. The need for a large rotational movement lessens the utility of these wrenches. If a large degree of motion is required to rotate the ratchet, the wrench cannot be used in smaller spaces. Attempts are also known in the art to create more efficient ratcheting mechanisms.
A need exists for an open-ended ratchet wrench assembly that can rotate a ratchet within small degrees, known as ratcheting arc to a person of ordinary skill in the art.
It is desirable to introduce an open-ended box wrench using a ratchet and dual pawl system which can operate at small rotational degrees (ratcheting arc) and which can be affordably manufactured and mass produced, and which does not require specialized parts or multi-component pawl assemblies.